This invention relates, generally, to the identification of materials and, more particularly, to the classification of structurally similar objects according to the materials of construction.
In the operation of plants where corrosive materials such as sulfuric acid are used or made, it is necessary to determine the extent of corrosion in transfer pipes and this is often accomplished by ultrasonic thickness measurements. Before making such a measurement, it is first necessary to know the material of the pipe, for example, in the case of a transfer pipe for sulfuric acid, whether the pipe is gray or ductile cast iron. Both types are found in the plants as well as in stock piles from which replacement lengths are selected. In these and other instances, there is a need for portable equipment with which pipes and similar objects can be identified quickly and positively.